diff --git a/java/ql/lib/semmle/code/java/frameworks/Regex.qll b/java/ql/lib/semmle/code/java/frameworks/Regex.qll
index f63f46c3878..56be77eae82 100644
--- a/java/ql/lib/semmle/code/java/frameworks/Regex.qll
+++ b/java/ql/lib/semmle/code/java/frameworks/Regex.qll
@@ -4,11 +4,46 @@ module;
 
 import java
 
+/** The class `java.util.regex.Matcher`. */
+class TypeRegexMatcher extends Class {
+  TypeRegexMatcher() { this.hasQualifiedName("java.util.regex", "Matcher") }
+}
+
+/**
+ * The `matches` method of `java.util.regex.Matcher`.
+ */
+class MatcherMatchesMethod extends Method {
+  MatcherMatchesMethod() {
+    this.getDeclaringType() instanceof TypeRegexMatcher and
+    this.hasName("matches")
+  }
+}
+
 /** The class `java.util.regex.Pattern`. */
 class TypeRegexPattern extends Class {
   TypeRegexPattern() { this.hasQualifiedName("java.util.regex", "Pattern") }
 }
 
+/**
+ * The `matches` method of `java.util.regex.Pattern`.
+ */
+class PatternMatchesMethod extends Method {
+  PatternMatchesMethod() {
+    this.getDeclaringType() instanceof TypeRegexPattern and
+    this.hasName("matches")
+  }
+}
+
+/**
+ * The `matcher` method of `java.util.regex.Pattern`.
+ */
+class PatternMatcherMethod extends Method {
+  PatternMatcherMethod() {
+    this.getDeclaringType() instanceof TypeRegexPattern and
+    this.hasName("matcher")
+  }
+}
+
 /** The `quote` method of the `java.util.regex.Pattern` class. */
 class PatternQuoteMethod extends Method {
   PatternQuoteMethod() {
diff --git a/java/ql/lib/semmle/code/java/security/Sanitizers.qll b/java/ql/lib/semmle/code/java/security/Sanitizers.qll
index 3dac78cf1e0..3f909864d2c 100644
--- a/java/ql/lib/semmle/code/java/security/Sanitizers.qll
+++ b/java/ql/lib/semmle/code/java/security/Sanitizers.qll
@@ -5,6 +5,7 @@ module;
 import java
 private import semmle.code.java.controlflow.Guards
 private import semmle.code.java.dataflow.DataFlow
+private import semmle.code.java.frameworks.Regex
 
 /**
  * A node whose type is a simple type unlikely to carry taint, such as primitives and their boxed counterparts,
@@ -40,12 +41,25 @@ class SimpleTypeSanitizer extends DataFlow::Node {
  * make the type recursive. Otherwise use `RegexpCheckBarrier`.
  */
 predicate regexpMatchGuardChecks(Guard guard, Expr e, boolean branch) {
-  guard =
-    any(MethodCall method |
-      method.getMethod().getName() = "matches" and
-      e = method.getQualifier() and
-      branch = true
+  exists(Method method, MethodCall mc |
+    method = mc.getMethod() and
+    guard = mc and
+    branch = true
+  |
+    // `String.matches` and other `matches` methods.
+    method.getName() = "matches" and
+    e = mc.getQualifier()
+    or
+    method instanceof PatternMatchesMethod and
+    e = mc.getArgument(1)
+    or
+    method instanceof MatcherMatchesMethod and
+    exists(MethodCall matcherCall |
+      matcherCall.getMethod() instanceof PatternMatcherMethod and
+      e = matcherCall.getArgument(0) and
+      DataFlow::localExprFlow(matcherCall, mc.getQualifier())
     )
+  )
 }
 
 /**
diff --git a/java/ql/test/query-tests/security/CWE-918/RequestForgery.expected b/java/ql/test/query-tests/security/CWE-918/RequestForgery.expected
index 555279c2a96..66dc968cb23 100644
--- a/java/ql/test/query-tests/security/CWE-918/RequestForgery.expected
+++ b/java/ql/test/query-tests/security/CWE-918/RequestForgery.expected
@@ -252,10 +252,6 @@
 | SanitizationTests.java:119:25:119:32 | unsafer9 | SanitizationTests.java:117:33:117:63 | getParameter(...) : String | SanitizationTests.java:119:25:119:32 | unsafer9 | Potential server-side request forgery due to a $@. | SanitizationTests.java:117:33:117:63 | getParameter(...) | user-provided value |
 | SanitizationTests.java:122:60:122:79 | new URI(...) | SanitizationTests.java:121:94:121:125 | getParameter(...) : String | SanitizationTests.java:122:60:122:79 | new URI(...) | Potential server-side request forgery due to a $@. | SanitizationTests.java:121:94:121:125 | getParameter(...) | user-provided value |
 | SanitizationTests.java:123:25:123:33 | unsafer10 | SanitizationTests.java:121:94:121:125 | getParameter(...) : String | SanitizationTests.java:123:25:123:33 | unsafer10 | Potential server-side request forgery due to a $@. | SanitizationTests.java:121:94:121:125 | getParameter(...) | user-provided value |
-| SanitizationTests.java:139:58:139:73 | new URI(...) | SanitizationTests.java:137:30:137:58 | getParameter(...) : String | SanitizationTests.java:139:58:139:73 | new URI(...) | Potential server-side request forgery due to a $@. | SanitizationTests.java:137:30:137:58 | getParameter(...) | user-provided value |
-| SanitizationTests.java:140:29:140:31 | r12 | SanitizationTests.java:137:30:137:58 | getParameter(...) : String | SanitizationTests.java:140:29:140:31 | r12 | Potential server-side request forgery due to a $@. | SanitizationTests.java:137:30:137:58 | getParameter(...) | user-provided value |
-| SanitizationTests.java:147:58:147:73 | new URI(...) | SanitizationTests.java:144:30:144:58 | getParameter(...) : String | SanitizationTests.java:147:58:147:73 | new URI(...) | Potential server-side request forgery due to a $@. | SanitizationTests.java:144:30:144:58 | getParameter(...) | user-provided value |
-| SanitizationTests.java:148:29:148:31 | r13 | SanitizationTests.java:144:30:144:58 | getParameter(...) : String | SanitizationTests.java:148:29:148:31 | r13 | Potential server-side request forgery due to a $@. | SanitizationTests.java:144:30:144:58 | getParameter(...) | user-provided value |
 | SpringSSRF.java:32:39:32:59 | ... + ... | SpringSSRF.java:28:33:28:60 | getParameter(...) : String | SpringSSRF.java:32:39:32:59 | ... + ... | Potential server-side request forgery due to a $@. | SpringSSRF.java:28:33:28:60 | getParameter(...) | user-provided value |
 | SpringSSRF.java:33:35:33:48 | fooResourceUrl | SpringSSRF.java:28:33:28:60 | getParameter(...) : String | SpringSSRF.java:33:35:33:48 | fooResourceUrl | Potential server-side request forgery due to a $@. | SpringSSRF.java:28:33:28:60 | getParameter(...) | user-provided value |
 | SpringSSRF.java:34:34:34:47 | fooResourceUrl | SpringSSRF.java:28:33:28:60 | getParameter(...) : String | SpringSSRF.java:34:34:34:47 | fooResourceUrl | Potential server-side request forgery due to a $@. | SpringSSRF.java:28:33:28:60 | getParameter(...) | user-provided value |
@@ -781,22 +777,6 @@ edges
 | SanitizationTests.java:122:68:122:78 | unsafeUri10 : String | SanitizationTests.java:122:60:122:79 | new URI(...) | provenance | MaD:285 Sink:MaD:6 |
 | SanitizationTests.java:122:68:122:78 | unsafeUri10 : String | SanitizationTests.java:122:60:122:79 | new URI(...) : URI | provenance | Config |
 | SanitizationTests.java:122:68:122:78 | unsafeUri10 : String | SanitizationTests.java:122:60:122:79 | new URI(...) : URI | provenance | MaD:285 |
-| SanitizationTests.java:137:30:137:58 | getParameter(...) : String | SanitizationTests.java:139:66:139:72 | param12 : String | provenance | Src:MaD:277  |
-| SanitizationTests.java:139:35:139:74 | newBuilder(...) : Builder | SanitizationTests.java:139:35:139:82 | build(...) : HttpRequest | provenance | MaD:283 |
-| SanitizationTests.java:139:35:139:82 | build(...) : HttpRequest | SanitizationTests.java:140:29:140:31 | r12 | provenance | Sink:MaD:4 |
-| SanitizationTests.java:139:58:139:73 | new URI(...) : URI | SanitizationTests.java:139:35:139:74 | newBuilder(...) : Builder | provenance | MaD:284 |
-| SanitizationTests.java:139:66:139:72 | param12 : String | SanitizationTests.java:139:58:139:73 | new URI(...) | provenance | Config Sink:MaD:6 |
-| SanitizationTests.java:139:66:139:72 | param12 : String | SanitizationTests.java:139:58:139:73 | new URI(...) | provenance | MaD:285 Sink:MaD:6 |
-| SanitizationTests.java:139:66:139:72 | param12 : String | SanitizationTests.java:139:58:139:73 | new URI(...) : URI | provenance | Config |
-| SanitizationTests.java:139:66:139:72 | param12 : String | SanitizationTests.java:139:58:139:73 | new URI(...) : URI | provenance | MaD:285 |
-| SanitizationTests.java:144:30:144:58 | getParameter(...) : String | SanitizationTests.java:147:66:147:72 | param13 : String | provenance | Src:MaD:277  |
-| SanitizationTests.java:147:35:147:74 | newBuilder(...) : Builder | SanitizationTests.java:147:35:147:82 | build(...) : HttpRequest | provenance | MaD:283 |
-| SanitizationTests.java:147:35:147:82 | build(...) : HttpRequest | SanitizationTests.java:148:29:148:31 | r13 | provenance | Sink:MaD:4 |
-| SanitizationTests.java:147:58:147:73 | new URI(...) : URI | SanitizationTests.java:147:35:147:74 | newBuilder(...) : Builder | provenance | MaD:284 |
-| SanitizationTests.java:147:66:147:72 | param13 : String | SanitizationTests.java:147:58:147:73 | new URI(...) | provenance | Config Sink:MaD:6 |
-| SanitizationTests.java:147:66:147:72 | param13 : String | SanitizationTests.java:147:58:147:73 | new URI(...) | provenance | MaD:285 Sink:MaD:6 |
-| SanitizationTests.java:147:66:147:72 | param13 : String | SanitizationTests.java:147:58:147:73 | new URI(...) : URI | provenance | Config |
-| SanitizationTests.java:147:66:147:72 | param13 : String | SanitizationTests.java:147:58:147:73 | new URI(...) : URI | provenance | MaD:285 |
 | SpringSSRF.java:28:33:28:60 | getParameter(...) : String | SpringSSRF.java:32:39:32:59 | ... + ... | provenance | Src:MaD:277 Sink:MaD:264 |
 | SpringSSRF.java:28:33:28:60 | getParameter(...) : String | SpringSSRF.java:33:35:33:48 | fooResourceUrl | provenance | Src:MaD:277 Sink:MaD:262 |
 | SpringSSRF.java:28:33:28:60 | getParameter(...) : String | SpringSSRF.java:34:34:34:47 | fooResourceUrl | provenance | Src:MaD:277 Sink:MaD:263 |
@@ -1701,20 +1681,6 @@ nodes
 | SanitizationTests.java:122:60:122:79 | new URI(...) : URI | semmle.label | new URI(...) : URI |
 | SanitizationTests.java:122:68:122:78 | unsafeUri10 : String | semmle.label | unsafeUri10 : String |
 | SanitizationTests.java:123:25:123:33 | unsafer10 | semmle.label | unsafer10 |
-| SanitizationTests.java:137:30:137:58 | getParameter(...) : String | semmle.label | getParameter(...) : String |
-| SanitizationTests.java:139:35:139:74 | newBuilder(...) : Builder | semmle.label | newBuilder(...) : Builder |
-| SanitizationTests.java:139:35:139:82 | build(...) : HttpRequest | semmle.label | build(...) : HttpRequest |
-| SanitizationTests.java:139:58:139:73 | new URI(...) | semmle.label | new URI(...) |
-| SanitizationTests.java:139:58:139:73 | new URI(...) : URI | semmle.label | new URI(...) : URI |
-| SanitizationTests.java:139:66:139:72 | param12 : String | semmle.label | param12 : String |
-| SanitizationTests.java:140:29:140:31 | r12 | semmle.label | r12 |
-| SanitizationTests.java:144:30:144:58 | getParameter(...) : String | semmle.label | getParameter(...) : String |
-| SanitizationTests.java:147:35:147:74 | newBuilder(...) : Builder | semmle.label | newBuilder(...) : Builder |
-| SanitizationTests.java:147:35:147:82 | build(...) : HttpRequest | semmle.label | build(...) : HttpRequest |
-| SanitizationTests.java:147:58:147:73 | new URI(...) | semmle.label | new URI(...) |
-| SanitizationTests.java:147:58:147:73 | new URI(...) : URI | semmle.label | new URI(...) : URI |
-| SanitizationTests.java:147:66:147:72 | param13 : String | semmle.label | param13 : String |
-| SanitizationTests.java:148:29:148:31 | r13 | semmle.label | r13 |
 | SpringSSRF.java:28:33:28:60 | getParameter(...) : String | semmle.label | getParameter(...) : String |
 | SpringSSRF.java:32:39:32:59 | ... + ... | semmle.label | ... + ... |
 | SpringSSRF.java:33:35:33:48 | fooResourceUrl | semmle.label | fooResourceUrl |
@@ -1857,10 +1823,3 @@ nodes
 | mad/Test.java:112:15:112:31 | (...)... | semmle.label | (...)... |
 | mad/Test.java:112:24:112:31 | source(...) : String | semmle.label | source(...) : String |
 subpaths
-testFailures
-| SanitizationTests.java:137:30:137:58 | getParameter(...) : String | Unexpected result: Source |
-| SanitizationTests.java:139:58:139:73 | new URI(...) | Unexpected result: Alert |
-| SanitizationTests.java:140:29:140:31 | r12 | Unexpected result: Alert |
-| SanitizationTests.java:144:30:144:58 | getParameter(...) : String | Unexpected result: Source |
-| SanitizationTests.java:147:58:147:73 | new URI(...) | Unexpected result: Alert |
-| SanitizationTests.java:148:29:148:31 | r13 | Unexpected result: Alert |